Zephyr sample iso_broadcaster does not work with connectkit_nrf52840

[whati001]

Hi All,

I am currently trying to get the sample iso_broadcaster (and iso_receiver) of the official Zephyr up and running. Unfortunately, it does not work for me out of the box. It seems that the connectkit starts to advertise the iso channel, but it never establishes successfully a BIG. Meaning, it never exchanges data with the iso_receiver.

Testing setup:

• Zephyr 3.6
• iso_broadcaster -> connectkit_nrf52840
• iso_receiver -> nrf54840dk

Has somebody already tried to run the BLE ISO samples on the connectkit?

Regards
Andi

[caizelin]

@whati001 I will check that and finally will push a working sample here:ncs-playground

[whati001]

@caizelin Thank you very much for your feedback !!!!
The samples work for me if I use a connectkit-nrf52840 as iso_broadcast and iso_receive.

But the iso communication does not work if I use different development boards, for example:

• iso_broadcast: connectkit-nrf52840
• iso_receive: nrf52840dk_nrf52840

In this case, I receive the following log on the dk.

Periodic sync established.
Waiting for BIG info...
Periodic sync established.
Create BIG Sync...
success.
Waiting for BIG sync chan 0...
PER_ADV_SYNC[0]: [DEVICE]: 0C:B6:E5:CC:42:46 (random) sync terminated
ISO Channel 0x2000031c disconnected with reason 0x3e
ISO Channel 0x20000330 disconnected with reason 0x3e
failed (err -11)
BIG Sync Terminate...failed (err -22)

I am aware that this is not any longer related to the connectkit hardware, but maybe you can help me out to also get this iso channel (between the connectkit <> nordic dev boards) also to work.

Thanks in advise.

[caizelin]

@whati001 These examples should also work on nordic dev boards. You can try to make a chip erase on the nordic dev boards and try again. If still not work, you can check nordic dev boards' configurations to find the difference with our boards.

[whati001]

@caizelin Indeed, this samples also work for nordic boards.
But as mentioned already multiple times, my root problem for this ticket was related to interoperability between your makerdiary board and the official nordik dks. After some more testing, I finally figured out that the iso channel never worked due to the selected 32kHz external crystal.

Based on my testing, it appears that there is a (for iso channels) significant clock drift between the official nordik dks and your connectkit board. If I use the internal RC (activated via KConfig CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y) the iso channel works between the nordic and your board. Guess synthesized clock (KConfig CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH) works too, but not tested yet.

Unfortunately, I have not found any BOM for the connectsdk board. Maybe you can share with us which crystal is used for EXT LF clock. Maybe we can use it by selecting the correct ppm calibration value. This would reduce current consumption too.

[whati001]

Default clock calibration is set to CONFIG_CLOCK_CONTROL_NRF_K32SRC_50PPM

[caizelin]

@whati001 The LF crystal mounted on our board is FC2012AN from EPSON, which comes with +/- 20ppm frequency tolerance. You can try to set the CONFIG_CLOCK_CONTROL_NRF_K32SRC_20PPM option.

[whati001]

I will close the question, using the internal 32kHz LF clock and changing the clock calibration value solved the issue for me.
To establish a connection with the nordic dk, I had to enable KConfig CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC.
To establish a connection with the holyiot dongle, it was sufficient to use KConfig CONFIG_CLOCK_CONTROL_NRF_K32SRC_20PPM